how do you explain why the addition of silver nitrate to the Fe/SCN equilibrium had an effect on the equilibrium, even though neither silver ion nor nitrate ion is written as part of the equilibrium reaction?
The addition of silver nitrate to the Fe/SCN equilibrium affects the Ag+ ion. Ag+ reacts with the SCN to form a precipitate. It is not a part of the equilibrium reaction, but it changes the concentration and removes SCN ions. This causes equilibrium to favor the reactants and make SCN to reach equilibrium.
